Objective: To compare the bleeding patterns obtained with two continuous combined and two sequential regimens of conjugated estrogens with medroxyprogesterone acetate (MPA) and conjugated estrogens alone.
Methods: This was a 1-year double-blind, randomized study done with 1724 postmenopausal women at 99 sites in the United States and Europe. All five treatment groups received 0.625 mg/day of conjugated estrogens. Groups A and B also took continuous daily doses of 2.5 and 5.0 mg of MPA, respectively. Groups C and D took 5.0 and 10.0 mg of MPA, respectively, for the last 14 days of each 28-day cycle. Group E took continuous daily doses of placebo to match MPA.
Results: The two continuous combined regimens (A and B) produced amenorrhea in 61.4 and 72.8%, respectively, of all evaluable cycles. Generally, the incidence of amenorrhea increased and irregular bleeding decreased with longer duration of treatment. In addition, amenorrhea occurred for at least the last seven consecutive cycles of the treatment year for about 40% of the patients taking the lower-dose continuous combined regimen (A), about 50% of the patients taking the higher-dose continuous combined regimen (B), and about 50% of the patients taking conjugated estrogens alone. About 5% of the patients who took either of the sequential regimens (C or D) had amenorrhea during that time. Most of the cycles (81.3 and 77.0% in groups C and D, respectively) for patients taking the sequential conjugated estrogens-MPA regimens had regular withdrawal bleeding or withdrawal spotting. There was no bleeding or spotting in 75.5% of the cycles for patients who took conjugated estrogens alone.
Conclusions: Approximately half of the women who took the continuous combined conjugated estrogens-MPA regimens had amenorrhea, and the incidence tended to increase during the study. Women who took the sequential regimens had good cycle control with minimal irregular bleeding. More than half of those who took conjugated estrogens alone had amenorrhea.